Evolution Evolution – populations change over time Current theory – life forms have descended from previous forms through changes in structure/function. Example often cited: horse feet. Occurs SLOWLY

Cited Evidence Fossils – evolutionists say that organisms have become more complex over time Homologous structures – those that have similar structures but different functions (bird wing compared to human arm and whale flipper) – evolutions say this is evidence of descent from a common ancestor Vestigial organs – those that serve no function. Examples cited – human tail bone and appendix. Evolutionists say this is evidence of organs in an ancestor which lost their function.

Darwin’s Finches The beaks are different shapes – corresponding to different feeding habits

Theories of Evolution Lamark – acquired characteristics (giraffe necks) – WRONG Darwin – Natural Selection: –Organisms have natural variation (from mutations) –Those organisms better able to compete survive to reproduce –AKA survival of the fittest –Most used example: peppered moth –****Does NOT change an individual organism!!!!

Important Terms Mutation: change in DNA Natural Selection: change in gene frequencies as a result of differences in survival and reproduction among organisms Gene Flow: Change in the genetic traits as organisms enter or leave a population Genetic Drift: Random changes in gene frequencies over time

Adaptations Adaptation: an inherited characteristic that makes a species more suited to its environment (examples – tortoises; rabbits) NOT changes in an individual organism Instead, changes in the # of individuals that have the particular trait

Remember Survival of the fittest means that POPULATIONS evolve – NOT INDIVIDUAL ORGANISMS

Geographic Isolation Geographic isolation occurs when a population becomes separated by changes in the environment Example – changes in a river’s course, ponds in Death Valley

Convergent Evolution Adaptations of different species that make them more alike. Common in animals in similar environments Example: shape/fins of sharks, penguins and porpoises.

Divergent Evolution When organisms of the same species develop adaptations that make them more different. Common when separated into different environments. If many adaptations occur, new species are developed. Example: many species of birds from a common ancestor

Extinction Occurs when there is a sudden change in the environment with no time for adaptations Asteroids, habitat destruction, over- hunting

Biodiversity All the different life forms on the planet: The sum of all the genetic material of all organisms All ecosystems, all species, with all their DNA Biodiversity is reduced when man alters environments (over killing, pollution, kudzu)

The Fossil Record Fossil – any evidence of an organism left behind Examples: bones, molds (i.e. footprints) Fossilization begins when an organism is suddenly buried (volcano, for example). As sediments pile up over time, organism’s remains are transformed into a fossil

Fossil Terms Paleontology – the study of fossils Stratification – layers of sedimentary rock. Different fossils are found in different layers Fossils are dated by relative dating. The fossils themselves are not dated, but are considered older/younger based on which layer of rock they are found in.

Absolute Dating Radioactive Dating: –C-14 is present in all living things –Half life is 5700 years.

Geologic Record Evolutionists say that the earth is more than 4 billion years old, and that humans have existed for only a few hundred thousand years. So how do they come up with what was going on billions of years ago? Their key concept: uniformity – all geological processes going on now (faulting, erosion, etc) were also going on in the past.